package com.itheima.neibulei.demo;

public class Test {
    public static void main(String[] args) {
        System.out.println((double)(2.0-1.1));
        int length = "".length();
        System.out.println(length);
        StringBuilder sb = new StringBuilder();
        sb.append(123).append(true);


      String s=  new String();

    }
}
